UIO: add generic UIO platform driver

This patch adds a generic UIO platform driver. It eliminates the need for a
dedicated kernel module for simple platform devices. Users only need to
implement their irq handler in platform code and fill a struct uio_info
there. This helps avoiding code duplication as UIO platform drivers often
share a lot of common code.

Signed-off-by: Uwe Kleine-König <Uwe.Kleine-Koenig@digi.com>
Signed-off-by: Hans J. Koch <hjk@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

3 files changed, 126 insertions, 0 deletions

diff --git a/drivers/uio/Kconfig b/drivers/uio/Kconfig
index 78e139c935eb..2e9079df26b3 100644
--- a/drivers/uio/Kconfig
+++ b/drivers/uio/Kconfig
@@ -26,6 +26,13 @@ config UIO_CIF
           To compile this driver as a module, choose M here: the module
           will be called uio_cif.
 
+config UIO_PDRV
+        tristate "Userspace I/O platform driver"
+        help
+          Generic platform driver for Userspace I/O devices.
+
+          If you don't know what to do here, say N.
+
 config UIO_SMX
         tristate "SMX cryptengine UIO interface"
         default n
diff --git a/drivers/uio/Makefile b/drivers/uio/Makefile
index 18c45662431e..e00ce0def1a0 100644
--- a/drivers/uio/Makefile
+++ b/drivers/uio/Makefile
@@ -1,3 +1,4 @@
 obj-$(CONFIG_UIO)       += uio.o
 obj-$(CONFIG_UIO_CIF)   += uio_cif.o
+obj-$(CONFIG_UIO_PDRV)  += uio_pdrv.o
 obj-$(CONFIG_UIO_SMX)   += uio_smx.o
diff --git a/drivers/uio/uio_pdrv.c b/drivers/uio/uio_pdrv.c
new file mode 100644
index 000000000000..5d0d2e85d982
--- /dev/null
+++ b/drivers/uio/uio_pdrv.c
@@ -0,0 +1,118 @@
+/*
+ * drivers/uio/uio_pdrv.c
+ *
+ * Copyright (C) 2008 by Digi International Inc.
+ * All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ */
+#include <linux/platform_device.h>
+#include <linux/uio_driver.h>
+#include <linux/stringify.h>
+
+#define DRIVER_NAME "uio"
+
+struct uio_platdata {
+        struct uio_info *uioinfo;
+};
+
+static int uio_pdrv_probe(struct platform_device *pdev)
+{
+        struct uio_info *uioinfo = pdev->dev.platform_data;
+        struct uio_platdata *pdata;
+        struct uio_mem *uiomem;
+        int ret = -ENODEV;
+        int i;
+
+        if (!uioinfo || !uioinfo->name || !uioinfo->version) {
+                dev_dbg(&pdev->dev, "%s: err_uioinfo\n", __func__);
+                goto err_uioinfo;
+        }
+
+        pdata = kzalloc(sizeof(*pdata), GFP_KERNEL);
+        if (!pdata) {
+                ret = -ENOMEM;
+                dev_dbg(&pdev->dev, "%s: err_alloc_pdata\n", __func__);
+                goto err_alloc_pdata;
+        }
+
+        pdata->uioinfo = uioinfo;
+
+        uiomem = &uioinfo->mem[0];
+
+        for (i = 0; i < pdev->num_resources; ++i) {
+                struct resource *r = &pdev->resource[i];
+
+                if (r->flags != IORESOURCE_MEM)
+                        continue;
+
+                if (uiomem >= &uioinfo->mem[MAX_UIO_MAPS]) {
+                        dev_warn(&pdev->dev, "device has more than "
+                                        __stringify(MAX_UIO_MAPS)
+                                        " I/O memory resources.\n");
+                        break;
+                }
+
+                uiomem->memtype = UIO_MEM_PHYS;
+                uiomem->addr = r->start;
+                uiomem->size = r->end - r->start + 1;
+                ++uiomem;
+        }
+
+        while (uiomem < &uioinfo->mem[MAX_UIO_MAPS]) {
+                uiomem->size = 0;
+                ++uiomem;
+        }
+
+        pdata->uioinfo->priv = pdata;
+
+        ret = uio_register_device(&pdev->dev, pdata->uioinfo);
+
+        if (ret) {
+                kfree(pdata);
+err_alloc_pdata:
+err_uioinfo:
+                return ret;
+        }
+
+        platform_set_drvdata(pdev, pdata);
+
+        return 0;
+}
+
+static int uio_pdrv_remove(struct platform_device *pdev)
+{
+        struct uio_platdata *pdata = platform_get_drvdata(pdev);
+
+        uio_unregister_device(pdata->uioinfo);
+
+        return 0;
+}
+
+static struct platform_driver uio_pdrv = {
+        .probe = uio_pdrv_probe,
+        .remove = uio_pdrv_remove,
+        .driver = {
+                .name = DRIVER_NAME,
+                .owner = THIS_MODULE,
+        },
+};
+
+static int __init uio_pdrv_init(void)
+{
+        return platform_driver_register(&uio_pdrv);
+}
+
+static void __exit uio_pdrv_exit(void)
+{
+        platform_driver_unregister(&uio_pdrv);
+}
+module_init(uio_pdrv_init);
+module_exit(uio_pdrv_exit);
+
+MODULE_AUTHOR("Uwe Kleine-Koenig");
+MODULE_DESCRIPTION("Userspace I/O platform driver");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:" DRIVER_NAME);